Bacteria In Inflammatory Bowel Disease Research Articles

Gut Microbiome-Related Anti-Inflammatory Effects of Aryl Hydrocarbon Receptor Activation on Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD) is one of the most prevalent chronic inflammations of the gastrointestinal tract (GIT). The gut microbial population, the cytokine milieu, the aryl hydrocarbon receptor (AHR) expressed by immune and nonimmune cells and the intrinsic pathway of Th-cell differentiation are implicated in the immunopathology of IBD. AHR activation requires a delicate balance between regulatory and effector T-cells; loss of this balance can cause local gut microbial dysbiosis and intestinal inflammation. Thus, the study of the gut microbiome in association with AHR provides critical insights into IBD pathogenesis and interventions. This review will focus on the recent advancements to form conceptional frameworks on the benefits of AHR activation by commensal gut bacteria in IBD.

Butyrate reduces adherent-invasive E. coli-evoked disruption of epithelial mitochondrial morphology and barrier function: involvement of free fatty acid receptor 3

ABSTRACT Gut bacteria provide benefits to the host and have been implicated in inflammatory bowel disease (IBD), where adherent-invasive E. coli (AIEC) pathobionts (e.g., strain LF82) are associated with Crohn’s disease. E. coli-LF82 causes fragmentation of the epithelial mitochondrial network, leading to increased epithelial permeability. We hypothesized that butyrate would limit the epithelial mitochondrial disruption caused by E. coli-LF82. Human colonic organoids and the T84 epithelial cell line infected with E. coli-LF82 (MOI = 100, 4 h) showed a significant increase in mitochondrial network fission that was reduced by butyrate (10 mM) co-treatment. Butyrate reduced the loss of mitochondrial membrane potential caused by E. coli-LF82 and increased expression of PGC-1 α mRNA, the master regulator of mitochondrial biogenesis. Metabolomics revealed that butyrate significantly altered E. coli-LF82 central carbon metabolism leading to diminished glucose uptake and increased succinate secretion. Correlating with preservation of mitochondrial network form/function, butyrate reduced E. coli-LF82 transcytosis across T84-cell monolayers. The use of the G-protein inhibitor, pertussis toxin, implicated GPCR signaling as critical to the effect of butyrate, and the free fatty acid receptor three (FFAR3, GPR41) agonist, AR420626, reproduced butyrate’s effect in terms of ameliorating the loss of barrier function and reducing the mitochondrial fragmentation observed in E. coli-LF82 infected T84-cells and organoids. These data indicate that butyrate helps maintain epithelial mitochondrial form/function when challenged by E. coli-LF82 and that this occurs, at least in part, via FFAR3. Thus, loss of butyrate-producing bacteria in IBD in the context of pathobionts would contribute to loss of epithelial mitochondrial and barrier functions that could evoke disease and/or exaggerate a low-grade inflammation.

DOP48 Key Anti-Inflammatory Faecalibacterium prausnitzii is Heterogeneous and Diverse in the East and West and in Health and Crohn’s disease. The ENIGMA study.

Abstract Background There is insufficient knowledge about the key characteristics of the pathogenic and protective bacteria in inflammatory bowel disease. The ENIGMA study aimed to identify the phylogenetic and functional characteristics of Faecalibacterium prausnitzii, considered a protective “anti-inflammatory” bacterium, in both health and Crohn’s disease in populations in the West (high Crohn’s incidence) and Hong Kong (rapidly increasing Crohn’s incidence). Methods Total DNA was extracted from tissue (right colon and terminal ileum) and stool collected from case-control cohorts in Hong Kong (n=51; 30 Crohn’s, 21 controls) and Australia (n=49; 29 Crohn’s, 20 controls). In parallel, the colonic mucosa-associated microbiota (MAM) for each subject was cultured from anaerobically preserved tissue. Shotgun metagenomic sequencing was used to characterise the stool and colonic MAM, augmented with 16S rRNA gene profiling and F. prausnitzii qPCR. The HUMANn3 and/or QIIME2 packages were used for the taxonomic and/or functional characterisation of the datasets. Metagenome-assembled genomes (MAG) were also produced from colonic MAM datasets using the MetaWRAP pipeline, and taxonomy deduced using the Genome Taxonomy Database-Tool kit (GTDB-tk). Results F. prausnitzii was detected in all case-control cohorts from Hong Kong and Australia. However, the prevalence was greater for the colonic MAM cultures of the Australian subjects, which provided 24/32 high-quality Faecalibacterium-affiliated MAG. No less than 6 different species-level lineages were predicted by GTDB-tk, and a similar phylogeny predicted using the gene encoding immunomodulatory peptides (mam). Functional features for the MAG from Crohn’s disease and control subjects were compared, and genes involved with histidine, riboflavin, purine and pyrimidine metabolism, pentose phosphate pathway, and oxidoreductases were enriched in the control subject MAG. In contrast, MAG derived from Crohn’s disease subjects possessed more functions putatively assigned to antibiotic resistance mechanisms and other protective functions. Differences were also observed in the carbohydrate-active enzyme profiles of the MAG recovered from Crohn’s disease and control subjects. Conclusion The populations of F. prausnitzii recovered from the colonic mucosa associated microbiota are both diverse and vary between Crohn’s disease and control subjects in both countries. The differences include metabolic and physiological characteristics. Therapeutic modification of F. prausnitzii needs to consider phylogenetic and functional characteristics. The ENIGMA study is supported by a grant from the Leona M. and Harry B. Helmsley Charitable Trust

The role of gut microbiome in inflammatory bowel disease diagnosis and prognosis.

Inflammatory bowel disease (IBD) is a chronic immune-mediated intestinal disease consisting of ulcerative colitis and Crohn's disease. Inflammatory bowel disease is believed to be developed as a result of interactions between environmental, immune-mediated and microbial factors in a genetically susceptible host. Recent advances in high-throughput sequencing technologies have aided the identification of consistent alterations of the gut microbiome in patients with IBD. Preclinical and murine models have also shed light on the role of beneficial and pathogenic bacteria in IBD. These findings have stimulated interest in development of non-invasive microbial and metabolite biomarkers for predicting disease risk, disease progression, recurrence after surgery and responses to therapeutics. This review briefly summarizes the current evidence on the role of gut microbiome in IBD pathogenesis and mainly discusses the latest literature on the utilization of potential microbial biomarkers in disease diagnosis and prognosis.

The role of oral bacteria in inflammatory bowel disease.

Over the past two decades, the importance of the microbiota in health and disease has become evident. Pathological changes to the oral bacterial microbiota, such as those occurring during periodontal disease, are associated with multiple inflammatory conditions, including inflammatory bowel disease. However, the degree to which this association is a consequence of elevated oral inflammation or because oral bacteria can directly drive inflammation at distal sites remains under debate. In this Perspective, we propose that in inflammatory bowel disease, oral disease-associated bacteria translocate to the intestine and directly exacerbate disease. We propose a multistage model that involves pathological changes to the microbial and immune compartments of both the oral cavity and intestine. The evidence to support this hypothesis is critically evaluated and the relevance to other diseases in which oral bacteria have been implicated (including colorectal cancer and liver disease) are discussed.

Comprehensive microbiota alterations in IBD and improved diagnostic accuracy for IBD using multi‐kingdom microbial features

Background Inflammatory bowel disease(IBD),including Crohn's Disease(CD) and ulcerative colitis (UC), is closely linked with altered gut microbiota.Roles of bacteria in IBD have been widely investigated, whereas other microbial kingdoms, fungi, archaea, virus, are less explored. Here, we aim to investigate the multi-kingdom microbial alterations and their capabilities for IBD diagnosis. Methods A total of 968 stool samples (292 CD, 305 UC and 371 controls) of untreated patients from iHMP were collected. Differential microorganisms were identified via wilcoxon test followed by adjustment for confounders. Inter-kingdom co-occurrence interactions analysis was performed by SparCC then microorganism modules were clustered by “MCODE”. Subsequently, neural networks algorithm was used to build diagnostic models for CD or UC with single- or multi-kingdom microbial features and the best panel of biomarkers was further identified by recursive feature elimination. Moreover, diagnostic models were validated in additional independent cohorts. Differential microbial pathways were analyzed to further explore functional alterations in CD and UC. Results In CD and UC, the microbial compositional change was identified in different kingdoms. Compared to controls, we identified 41 bacteria, 37 fungi, 40 archaea and 50 viruses with differential abundance in CD. Similarly, 63 bacteria, 52 fungi, 58 archaea and 39 viruses with differential abundance were detected in UC. Moreover, inter-kingdom interactions were more complex in IBD than controls, especially the interactions between fungal Aspergillusand BeAn 58058 virus. Notably, the diagnostic models constructed with multi-kingdom microbial features performed better (AUC of 0.90 in CD and 0.91 in UC) than that with single kingdom microbial features. The diagnostic models also showed reliable accuracy in independent cohorts with an average AUC of 0.93 (CD) and 0.74 (UC), respectively. Among these biomarkers, bacterial Bacteroidesand fungalAspergillusare the main contributors to the distinguishing ability in both CD and UC diagnostic models. In addition, pathways related to lipid and terpenoids metabolism and immune response were altered in CD and UC, such as glycosphingolipid biosynthesis, carotenoid biosynthesis and IL-17 signaling pathway. Conclusions Our study investigated comprehensivepathogenic microbiota of IBD, which encompasses bacteria, fungi, virus and archaea. And the combination of multi-kingdom microbial biomarkers may serve as effective tools for CD and UC diagnosis, which outperforms single kingdom biomarkers. The alterations of microbial inter-kingdom interactions and cross-kingdom functional changes provide new insight in understanding pathological mechanisms of IBD.

Metagenome Analysis of Intestinal Bacteria in Healthy People, Patients With Inflammatory Bowel Disease and Colorectal Cancer.

ObjectivesSeveral reports suggesting that the intestinal microbiome plays a key role in the development of inflammatory bowel disease (IBD) or colorectal cancer (CRC), but the changes of intestinal bacteria in healthy people, patients with IBD and CRC are not fully explained. The study aimed to investigate changes of intestinal bacteria in healthy subjects, patients with IBD, and patients with CRC.MaterialsWe collected data from the European Nucleotide Archive on healthy people and patients with colorectal cancer with the study accession number PRJEB6070, PRJEB7774, PRJEB27928, PRJEB12449, and PRJEB10878, collected IBD patient data from the Integrated Human Microbiome Project from the Human Microbiome Project Data Portal. We performed metagenome-wide association studies on the fecal samples from 290 healthy subjects, 512 IBD patients, and 285 CRC patients. We used the metagenomics dataset to study bacterial community structure, relative abundance, functional prediction, differentially abundant bacteria, and co-occurrence networks.ResultsThe bacterial community structure in both IBD and CRC was significantly different from healthy subjects. Our results showed that IBD patients had low intestinal bacterial diversity and CRC patients had high intestinal bacterial diversity compared to healthy subjects. At the phylum level, the relative abundance of Firmicutes in IBD decreased significantly, while the relative abundance of Bacteroidetes increased significantly. At the genus level, the relative abundance of Bacteroides in IBD was higher than in healthy people and CRC. Compared with healthy people and CRC, the main difference of intestinal bacteria in IBD patients was Bacteroidetes, and compared with healthy people and IBD, the main difference of intestinal bacteria in CRC patients was in Fusobacteria, Verrucomicrobia, and Proteobacteria. The main differences in the functional composition of intestinal bacteria in healthy people, IBD and CRC patients were L-homoserine and L-methionine biosynthesis, 5-aminoimidazole ribonucleotide biosynthesis II, L-methionine biosynthesis I, and superpathway of L-lysine, L-threonine, and L-methionine biosynthesis I. The results of stratified showed that the abundance of Firmicutes, Bacteroidetes, and Actinobacteria involved in metabolic pathways has significantly changed. Besides, the association network of intestinal bacteria in healthy people, IBD, and CRC patients has also changed.ConclusionsIn conclusion, compared with healthy people, the taxonomic and functional composition of intestinal bacteria in IBD and CRC patients was significantly changed.

OP10 IgA coating of intestinal microbiota is associated with inflammatory bowel disease in twin pairs discordant for inflammatory bowel disease

Abstract Background The pathogenesis of inflammatory bowel disease (IBD) is thought to result from an interplay between microbiota, the immune system and the environment in genetically susceptible hosts. Immunoglobulin A (IgA) produced by the immune system can be specifically directed against bacteria. The IgA-coating pattern of intestinal bacteria thus reflects interactions between the immune system and specific bacteria. Studying IBD in twins, concordant and discordant for IBD, reduces the impact of genetic predisposition and childhood exposures and therefore offers the unique opportunity to focus on other factors such as intestinal microbiota composition and immune-interactions in IBD. Methods Faecal samples from twin pairs discordant for Crohn’s disease (CD) or ulcerative colitis (UC) were collected. Employing fluorescence-activated cell sorting, IgA+ and IgA− bacteria from the intestinal microbiota were sorted. Subsequently, (1) the total, (2) IgA+ and (3) IgA− microbial composition was determined by 16S rRNA sequencing (IgA-SEQ). We estimated the relative IgA coating per bacterial species by dividing the abundance of that species in the IgA+ fraction over the abundance in the IgA- fraction, representing the IgA coating index. Linear discriminant analyses were performed with LefSE. Results We included 31 twin pairs (62 individuals) discordant for IBD (CD: 15, UC: 16). 15/32 twin pairs were monozygotic, 43/62 of participants were female, the median age was 47 years (interquartile range: 34–58.5). Of 31 participants with IBD, 7 had signs of active inflammation based on endoscopy, Harvey–Bradshaw index or short clinical colitis activity index. Differences (log-linear discriminant analysis score >3) in the microbial composition of IgA-coated bacteria were observed between CD patients and their twin-siblings not affected by IBD: Dorea formicigenerans (increased in IgA coating), Parabacteroides sp., Christensenellaceae sp., Clostridium sp. and Mollicutes RF39 sp. (decreased in IgA coating). In ulcerative colitis patients, an increase in IgA-coating was observed for Ruminococcus gnavus and Dorea formicigenerans, while Turicibacter sp., Barnesiellaceae sp. and an unclassified Clostridiales sp. were decreased in IgA-coating compared with their twin-siblings not affected by IBD. Conclusion In twins affected by IBD, the pattern of IgA-coated bacteria differs between IBD and non-IBD affected individuals. These data on immune-bacteria interactions could serve as a starting point for the elucidation of the immune-responses triggered by specific bacteria in IBD.

Dynamic immunoglobulin responses to gut bacteria during inflammatory bowel disease

ABSTRACT Aberrant immune responses against gut microbiota are thought to be key drivers of inflammatory bowel disease (IBD) pathogenesis. However, the extent and targets of immunoglobulin (Ig) A versus IgG responses to gut bacteria in IBD and its association with IBD severity is not well understood. Here, we address this by analyzing fecal samples from Crohn’s disease (CD), ulcerative colitis (UC), and Non-IBD patients by flow cytometry for the frequency of bacteria that were endogenously bound with IgA and/or IgG. Assessment of IBD patients from two geographically distinct cohorts revealed increased percentages of IgA- and IgG-bound fecal bacteria compared to non-IBD controls. Notably, the two major subsets of IBD showed distinct patterns of Ig-bound bacteria, with CD activity associated with increases in both IgA and IgG-bound bacteria, whereas UC activity correlated only with increases in IgG-bound bacteria. Analysis of the flow sorted Ig-bound bacterial repertoire by 16S rDNA sequencing revealed taxa that were Ig-bound specifically in IBD. Notably, this included bacteria that are also thought to reside in the oral pharynx, including Gemella, Peptostreptococcus, and Streptococcus species. These data show that the pattern of IgA and IgG binding to fecal bacteria is distinct in UC and CD. In addition, the frequency of Ig-bound fecal bacteria may have potential as a non-invasive biomarker for disease activity. Finally, our results support the hypothesis that immune responses to oral pharyngeal bacteria may play an important role in the pathogenesis of IBD.

Macrophage interactions with fungi and bacteria in inflammatory bowel disease.

In this review, we discuss recent advances into delineating the dual role of intestinal phagocytes in health and during intestinal disease. We further discuss the key role of gut-resident macrophages in recognition of bacterial and fungal microbiota in the gut. Inflammatory bowel disease (IBD) commonly manifests with pathologic changes in the composition of gut bacterial and fungal microbiota. Intestinal macrophages are key regulators of the balance between tolerogenic immunity and inflammation. Recent studies have highlighted the role of resident intestinal macrophages in the control of commensal fungi and bacteria in the steady state and during dysbiosis. The dual role of these cells in maintaining intestinal homeostasis and responding to microbiota dysbiosis during inflammation is being increasingly studied. It is becoming increasingly clear that an aberrant proinflammatory response to microbiota by infiltrating monocytes plays a role in the development of intestinal inflammation. Intestinal mononuclear phagocytes with characteristics of macrophages play an important role in limiting fungal and bacterial overgrowth under these conditions, but can be influenced by the inflammatory environment to further propel inflammation. Better understanding of the interaction of intestinal macrophages with host microbiota including commensal fungi and bacteria, provides an opportunity for the development of more targeted therapies for IBD.

Combination Antibiotics Improves Disease Activity and Alters Microbial Communities in Children With Ulcerative Colitis.

Combinations of antibiotics have shown promise in off-label treatment of Inflammatory Bowel Disease (IBD) flares in adult and pediatric patients1–6. In a small pediatric cohort of moderate-severe medically refractory Ulcerative Colitis (UC), half achieved remission with a regimen of 3–4 antibiotics6. The rationale is to decrease mucosal inflammation by altering intestinal microbiota, however, to date no study has documented these changes. We report our experience with combination oral antibiotics in symptomatic pediatric patients with steroid-dependent or -resistant UC, and demonstrate significant alterations in gut microbiota during and after antibiotic therapy with reductions in inflammatory markers.

Role of Lactic Acid Probiotic Bacteria in IBD.

IBD is considered as one of the major public health concerns worldwide. The pathophysiology and gut microbial alteration during inflammatory bowel disease (IBD) are still not completely understood. Gut microbiota is implicated in most of the gastro-intestinal (GI) diseases including IBD. From the time of gut microbiota establishment and through aging, it undergoes a lot of changes in the composition. In a healthy state, the composition of beneficial microbes in the gut is comparatively higher and due to factors such as malnutrition, use of antibiotics and any underlying diseases allow the colonization and invasion of pathogens. A careful manipulation of gut microbiota during disease conditions such as IBD is required. Probiotics are natural, safe and useful interventions for GI diseases. Lactic acid probiotic bacteria have shown many beneficial effects in various gastrointestinal and inflammatory disorders. This review focuses on the use of probiotics in IBD and possible mechanism of probiotics in inflammation conditions.

Intestinal Bacteria Composition and Translocation of Bacteria in Inflammatory Bowel Disease

BackgroundLive commensal intestinal bacteria are present in the peripheral blood where they can induce inflammation.ObjectiveTo evaluate the intestinal bacteria composition and translocation of bacteria in IBD.MethodsBoth blood and tissue biopsy samples were collected from adult patients with active/inactive Crohn’s disease (CD), active/inactive ulcerative colitis (UC) and healthy individuals. Most of the patients were newly diagnosed and none of them received antibiotics. Using a reverse transcription–quantitative real-time PCR (RT-qPCR) method, we determined the composition of microbiota. NOD2/CARD15 genotyping was also studied.ResultsTotal bacterial DNA concentration was increased in tissue and blood samples of IBD patients compared to healthy controls. Furthermore, the active IBD cases had higher total bacterial DNA concentration levels compared to the inactive cases. Three species characterized dysbiosis in IBD, namely an increase of Bacteroides spp in active and inactive IBD samples, and a decrease in Clostridium leptum group (IV), and Faecalibacterium prausnitzi in both active and inactive IBD patients. No significant association between bacterial translocation and NOD2/CARD15 mutations was found.ConclusionsThe composition of the microbiota in IBD patients differs from that of healthy controls. The high rate of bacterial DNA in the blood samples indicates translocation in inflammatory bowel disease.

Development of an Ex Vivo Organ Culture Technique to Evaluate Probiotic Utilization in IBD.

The consistent technical and conceptual progress in the study of the microbiota has led novel impulse to the research for therapeutical application of probiotic bacteria in human pathologies, such as inflammatory bowel disease (IBD). Considering the heterogenous results of probiotics in clinical studies, the model of translational medicine may lead to a more specific and efficacious utilization of probiotic bacteria in IBD. In this regard, the selection and utilization of appropriate experimental models may drive the transition from pure in vitro systems to practical clinical application. We developed a simple and reproducible ex vivo organ culture method with potential utilization for the evaluation of probiotic bacteria efficacy in IBD patients.

Role of bacteria in Inflammatory bowel disease (IBD)

Role of bacteria in Inflammatory bowel disease (IBD)

P052. Intestinal total bacteria concentration and translocation of bacteria in inflammatory bowel disease

P052. Intestinal total bacteria concentration and translocation of bacteria in inflammatory bowel disease

Pathological and therapeutic interactions between bacteriophages, microbes and the host in inflammatory bowel disease.

The intestinal microbiome is a dynamic system of interactions between the host and its microbes. Under physiological conditions, a fine balance and mutually beneficial relationship is present. Disruption of this balance is a hallmark of inflammatory bowel disease (IBD). Whether an altered microbiome is the consequence or the cause of IBD is currently not fully understood. The pathogenesis of IBD is believed to be a complex interaction between genetic predisposition, the immune system and environmental factors. In the recent years, metagenomic studies of the human microbiome have provided useful data that are helping to assemble the IBD puzzle. In this review, we summarize and discuss current knowledge on the composition of the intestinal microbiota in IBD, host-microbe interactions and therapeutic possibilities using bacteria in IBD. Moreover, an outlook on the possible contribution of bacteriophages in the pathogenesis and therapy of IBD is provided.

Gut Microbiota and Inflammatory Bowel Disease: The Role of Antibiotics in Disease Management

Imbalances in the composition and number of bacteria in the gut microbiota have been implicated in inflammatory bowel disease (IBD), and modulation of the gut microbiota by probiotics and antibiotics in IBD has been an active area of research, with mixed results. This narrative review summarizes the findings of relevant publications identified using the PubMed database. Although antibiotics have been associated with an increased risk of IBD development and flares, several meta-analyses demonstrate that antibiotics are efficacious for the induction of remission and treatment of flares in patients with IBD. Data supporting their use include a large number of antibiotic studies in Crohn's disease and evidence suggests antibiotics are efficacious in both Crohn's disease and ulcerative colitis, although there are fewer studies of the latter. For Crohn's disease, antibiotics have been shown to be useful for the induction of remission and in the postoperative management of patients undergoing surgery. Additionally, patients with fistulizing disease, particularly perianal, can benefit from antibiotics administered short term. Both antimicrobials and probiotics have been shown to be useful for the treatment of pouchitis. Additional randomized controlled trials are needed to further elucidate the role of bacteria in IBD and to better inform clinicians about appropriate antibiotic therapies.

Increased Proportions of Bifidobacterium and the Lactobacillus Group and Loss of Butyrate-Producing Bacteria in Inflammatory Bowel Disease

Dysbiosis in the intestinal microbiota of persons with inflammatory bowel disease (IBD) has been described, but there are still varied reports on changes in the abundance of Bifidobacterium and Lactobacillus organisms in patients with IBD. The aim of this investigation was to compare the compositions of mucosa-associated and fecal bacteria in patients with IBD and in healthy controls (HCs). Fecal and biopsy samples from 21 HCs, 21 and 15 Crohn's disease (CD) patients, and 34 and 29 ulcerative colitis (UC) patients, respectively, were analyzed by quantitative real-time PCR targeting the 16S rRNA gene. The bacterial numbers were transformed into relative percentages for statistical analysis. The proportions of bacteria were uniformly distributed along the colon regardless of the disease state. Bifidobacterium was significantly increased in the biopsy specimens of active UC patients compared to those in the HCs (4.6% versus 2.1%, P = 0.001), and the proportion of Bifidobacterium was significantly higher in the biopsy specimens than in the fecal samples in active CD patients (2.7% versus 2.0%, P = 0.012). The Lactobacillus group was significantly increased in the biopsy specimens of active CD patients compared to those in the HCs (3.4% versus 2.3%, P = 0.036). Compared to the HCs, Faecalibacterium prausnitzii was sharply decreased in both the fecal and biopsy specimens of the active CD patients (0.3% versus 14.0%, P < 0.0001 for fecal samples; 0.8% versus 11.4%, P < 0.0001 for biopsy specimens) and the active UC patients (4.3% versus 14.0%, P = 0.001 for fecal samples; 2.8% versus 11.4%, P < 0.0001 for biopsy specimens). In conclusion, Bifidobacterium and the Lactobacillus group were increased in active IBD patients and should be used more cautiously as probiotics during the active phase of IBD. Butyrate-producing bacteria might be important to gut homeostasis.

OC-074 The Role of the Fungal Microbiota in the Pathogenesis of De-Novo Paediatric Inflammatory Bowel Disease using next Generation Sequencing

<h3>Introduction</h3> Paediatric Inflammatory bowel disease (IBD) incidence is rising worldwide. Recently the role of the gut microbiota has been recognised as pivotal in disease pathogenesis. IBD microbial studies to date have focused on bacterial diversity assessment in established disease cohorts, with limited studies in treatment naive patients. In contrast to bacteria, the exact role of the colonising fungi and their pathogenic potential has not been fully explored. The aim of the study was to examine candidate fungal triggers at disease onset in children with IBD using pyrosequencing, utilising the Bacteria in Inflammatory bowel disease in Scottish Children Undergoing Investigation before Treatment (BISCUIT) study cohort. <h3>Methods</h3> 128 children undergoing colonoscopy were approached from three Scottish paediatric centres (Aberdeen, Glasgow and Dundee) with 100 ultimately recruited and biopsied; 44 IBD (comprising Crohn’s disease (CD; 29), ulcerative colitis (UC; 13) and IBD-type unspecified (2)), 42 normal colon controls (NCC) and 14 “others”. All IBD patient samples were taken from inflamed tissue. Fungal DNA was amplified on a reduced cohort of 37 recruits (13 CD, 12 UC, 12 NCC) using 18S rDNA primers. Roche 454 Titanium sequencing was conducted by NewGene (Newcastle, UK). Data analysis was performed using QIIME version 1.3.0 workflow. Taxonomy assignment of operational taxonomic units (OTUs) was performed according to ribosomal database project taxonomy. OTU tables were rarefied at 3,000 reads. <h3>Results</h3> Fungal DNA was amplifiable from 7 patient samples, 6 children with a diagnosis of IBD – 4 with CD (BISCUIT1, 31, 62 and 89), 2 children with UC (BISCUIT33 and 104) and 1 NCC (BISCUIT 27). Fungal diversity was assessed in all paediatric samples alongside three adult samples to act as comparison. The adult samples comprised 1 patient with UC (2UC21Aa) and 2 NCC (GH4 and GH9). Phylum level analysis indicated that all fungal sequences belonged to the Ascomycota and Basidiomycota phyla. Control patients contained predominantly Ascomycota sequences ( &gt; 80% of sequences in all patients) whilst 6/7 IBD patients contained exclusively Basidiomycota species. Genus level analysis was undertaken and there was no similarity between fungal profiles from the paediatric and adult samples. <h3>Conclusion</h3> By using robust methodology we have characterised the IBD “fungal microbiota” at diagnosis in children. Based on the current study, it would appear that a distinctly altered fungal species profile is present at IBD disease presentation. Further work should now focus on expanding this study and identifying how to beneficially modify the microbiota using established and novel IBD treatments. <h3>Disclosure of Interest</h3> None Declared